The Constrained Application Protocol (CoAP) is a protocol for allowing computer systems or devices to communicate by exchanging messages. The protocol specifies certain parameters related to message format and message exchange rules. Messages sent over CoAP can be relatively small in size, and therefore, CoAP allows communication between computer systems or devices with limited processing resources and/or limited storage resources. These computer systems or devices are sometimes referred to as “constrained nodes” or “constrained devices.”
To address security concerns associated with communication via CoAP messages, it has been suggested that messages sent over CoAP use Datagram Transport Layer Security (DTLS). Although DTLS can increase the security of communications, it does not provide for authentication of the sender of the CoAP message.